Thymosin Beta-4
Regenerative Peptideclinical_trialsAlso known as: Tβ4, TB4, TMSB4X, Full-Length Thymosin Beta-4
The full-length 43-amino acid peptide from which TB-500 is derived, with comprehensive tissue repair, anti-inflammatory, and regenerative properties across virtually all tissue types.
Overview
Thymosin Beta-4 (Tβ4) is a 43-amino acid naturally occurring peptide and the most abundant member of the beta-thymosin family. It is expressed in virtually all cell types and is a major actin-sequestering protein that regulates cell migration, differentiation, and survival. While TB-500 (the commercially available synthetic fragment) represents the active region of Thymosin Beta-4, the full-length peptide has additional biological activities. Tβ4 promotes wound healing, reduces inflammation, protects against fibrosis, and supports cardiac repair after injury. It was originally isolated from the thymus but is now known to be ubiquitously expressed. Clinical trials have been conducted for corneal wound healing (under the name RGN-259) and cardiac repair. The distinction between Tβ4 and TB-500 matters: TB-500 is the 17-amino acid active fragment (amino acids 17-23 being the key actin-binding domain), while Tβ4 is the complete molecule with potentially broader activity.
Mechanism of Action
Thymosin Beta-4 works through multiple pathways: (1) Sequesters G-actin monomers, regulating actin polymerization essential for cell migration; (2) Promotes endothelial cell migration and angiogenesis for tissue repair; (3) Reduces inflammatory cytokines (TNF-alpha, IL-1beta) and promotes anti-inflammatory IL-10; (4) Activates cardiac progenitor cells and promotes cardiomyocyte survival after ischemic injury; (5) Inhibits NF-κB signaling to reduce inflammation; (6) Promotes hair follicle stem cell migration and differentiation; (7) Reduces fibrosis and scar formation during wound healing; (8) Protects cells from oxidative stress via upregulation of antioxidant enzymes.
Molecular Formula
C212H350N56O78S1
Molecular Weight
4963.5 g/mol
Sequence
Ac-Ser-Asp-Lys-Pro-Asp-Met-Ala-Glu-Ile-Glu-Lys-Phe-Asp-Lys-Ser-Lys-Leu-Lys-Lys-Thr-Glu-Thr-Gln-Glu-Lys-Asn-Pro-Leu-Pro-Ser-Lys-Glu-Thr-Ile-Glu-Gln-Glu-Lys-Gln-Ala-Gly-Glu-Ser
Dosage Protocols
Dose Range
750mcg – 2mg
Frequency
Twice weekly
Route
subcutaneous
Cycle Length
4-12 weeks
Similar protocols to TB-500. Full-length Tβ4 may have longer duration of action. Loading phase of 4-6 weeks followed by maintenance.
Source: Clinical research and community protocols
🧮 Personalized Dosage Calculator
💰 Estimated Pricing
Typical Supply
5mg vial
Last Updated
2026-02
Full-length TB4 protein. More expensive than TB-500 fragment. Research: $40-80. Telehealth: $150-300/mo. Healing and repair.
⚠️ Prices are estimates based on publicly available data and may vary significantly by vendor, location, and prescription status. This is not medical or financial advice.
Side Effects
| Effect | Severity |
|---|---|
| Injection site reaction | mild |
| Fatigue | mild |
| Headache | mild |
| Flu-like symptoms | mild |
Pros & Cons
Full-length molecule may have broader biological activity than TB-500 fragment
Extensive preclinical evidence for cardiac repair, wound healing, and anti-fibrotic effects
Clinical trials underway for corneal healing (RGN-259) with promising results
Anti-inflammatory without immunosuppression — modulates rather than suppresses
More expensive than TB-500 due to larger molecule and complex synthesis
Less widely available than TB-500 in the research peptide market
Not yet clear if full-length provides clinically meaningful benefits over TB-500 fragment
Banned in competitive sports
Research Studies
🩸 Blood Work
No specific bloodwork requirements reported for this peptide. General health panels are always recommended before starting any peptide protocol.
Legal Status
Not FDA-approved. RGN-259 (ophthalmic formulation) has undergone clinical trials. Available as a research chemical. Banned by WADA. TB-500 (fragment) is more commonly available.
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